Urethane was nominated for study because of widespread exposure of the general population to urethane from alcoholic beverages and a lack of adequate toxicity and carcinogenicity data on the dose-response effects. The objective of this contract is to characterize the toxicity of urethane in Fischer 344 rats and B6C3F1 mice and to examine the effect of ethanol on the toxicity of urethane. Animals will be dosed with urethane, urethand and ethanol, or ethanol in the drinking water for 13-weeks. At the conclusion of the dosing period general toxicity and target organ toxicity will be evaluated.